WoW Skinning

[Rayz]

World of Warcraft Skinning Info/Tutorial
Written by Troll Paxton
Part 1: The Blizzard File System
Blizzard stores its assets (all the textures, models, sounds, etc) in what they call MPQ files. All of the MPQ files are in the [WoW]\Data directory. [Throughout this I will refer to the WoW directory as [WoW]. If you installed to the default directory, [WoW] = C:\Program Files\World Of Warcraft.] MPQ files have directories, just like hard drives or ZIP files. [Directory is just another word for Folder.] This is important because when WoW goes to load a file, it looks for it within a specific "directory" within an MPQ file.
Blizzard finds MPQ files handy to use for various reasons, but they have one big drawback. Lets say that in a given patch they just want to change a few files within a big MPQ file. They would have to include the whole MPQ in their patch download, and that is bad because several of these MPQs are very large. So, Bliz came up with a clever system for getting around this problem, which works like this. When WoW goes to load an asset, it first looks in the MPQ it expects it to be in. It then looks for other, patch MPQs with given names, and if it finds them it loads them one by one and searches for the asset in them. If it finds a version of the asset in a patch MPQ it uses it instead of the regular version.
Patch MPQs are all named "Patch-$.mpq", where $ is a number 1-9 or a letter a-z. WoW will actually look for the patch MPQs in that order, and whenever it finds a file in a patch MPQ it uses it instead of any previous versions it found, we can use that system to prioritize our MPQs. For example, a given texture in Patch-a.mpq gets ignored if it is found in Patch-z.mpq. We are getting ahead of ourselves a little bit, though...
In a nutshell, the patch MPQ system is what allows us to "change" game textures without actually changing the game MPQs, which would be slow and potentially dangerous. We can take our textures and put them into a new MPQ and, if we've named everything correctly, WoW will load it.
Important historical note : Prior to patch 1.11 or so, the patch system actually would search your local directories after searching for patch MPQs. All you had to do to replace a game texture was just put the file into the proper subdirectory and WoW would load it. Why do I mention this after they've taken it out? Because this is how WoWModelViewer [I'll abbreviate this to WMV from here on out] reads local files. We'll learn why that program rocks in a little bit.
Example time! Lets say that we've got a modified version of a Night Elf skin and we want to put it into a custom MPQ. The original texture is in Texture.mpq, like so:
[Texture.mpq] Character\NightElf\Female\NightElfFemaleSkin00_00.blp
For this example, let's say we installed WoW to the default folder. If we want to preview our modified version of this skin in WMV, then we'd need to put it here:
C:\Program Files\World of Warcraft\Data\Character\NightElf\Female\NightElfFemaleSkin00_00.blp
Finally, if we want to see the texture in the game, we'd make a new MPQ file [I'll explain how later] using the patch naming convention and put in our texture, making sure to keep the same directory structure:
[Patch-a.mpq] Character\NightElf\Female\NightElfFemaleSkin00_00.blp
Part 2: Working With MPQ files
Now that we know what MPQ files are and how WoW loads assets from them, lets talk about what tools are available that we can use to work with them.
For reading MPQ files , nothing compares to MyWarcraftStudio [MWS] because if you select a texture it shows you what the texture is! That and the author is very good at updating it when Blizzard decides to make a change to the MPQ format (which is pretty often). The best place to download this program is from from the author's blog: 平民程序 - linghuye's blog - IT博客网.
For writing/creating MPQ files , MWS will work but there is also another great tool called WinMPQ. WinMPQ's big advantage over MWS is that you can write scripts to automate the creation of MPQs. There are several versions of WinMPQ floating about. I get the one called "MyWinMPQ" from http://www.wowinterface.com/.
Before we go on, we need to cover one really important point. The MPQ file format supports a few different types of file compression. Our tools don't necessarily support them all! Specifically, MWS *does* let you use compression when creating new MPQs, but WinMPQ doesn't. Luckily, WoW doesn't seem to care either way, so your safest bet when creating new MPQs is to find out how to disable compression with whatever tool you are using.
Example time! Lets write a script for WinMPQ that creates a MPQ for our NElf texture, and a batch file to run it for us. First, the script. It's pretty basic stuff: one line to define that you are creating a new MPQ, and then one line for each of the files you want to add to it. The x line at the end just tells WinMPQ to exit when it is done. One of the cool things about this system is that if you run your script from the [WoW]\Data directory, not only will the relative path ("Character\NightElf\Female\") define where WinMPQ is to find the texture, it will also create that directory structure in the MPQ. (Remember that we need to keep the directory structure for our files or WoW won't find them.) Here is the script:
--- Patch-a.txt ---
n patch-a.mpq
a "Character\NightElf\Female\NightElfFemaleSkin00_00.blp"
x
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You can open WinMPQ and load script files manually using the UI, but its easier to write a batch file to do it. Lets say we installed WinMPQ to C:\WinMPQ. Make this batch file and put it in your WoW Data directory:
--- MakePatchA.bat ---
C:\WinMPQ\WinMPQ.exe s patch-a.txt
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Now all you have to do is run the batch file and your modified texture will be visible in-game!
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If you do not want to make a batch file - you can open up mywinmpq and go to File --> Run MoPaQ 2000 Script
Under, File Type switch it to All Files (*.*) and select teh text fiel you wrote
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Part 3: How WoW Draws Characters
The first thing draw on a character model is the base Skin texture, ex. NightElfFemaleSkin00_00.blp. This is a Barbie-doll texture: no naughty-bits. Different skin tones are different numbers, ex. NightElfFemaleSkin00_01.blp, NightElfFemaleSkin00_02.blp, etc. WoW will only be able to draw base skins correctly if they are palettized textures without alpha. You should be aware that the number of different skin textures is defined by a number somewhere else (I'm not sure where), and so just adding new textures with incremented numbers will not give you more skin color options.
If your character isn't wearing any chest armor, WoW draws another texture on top of the model's chest that has underwear on it, ex. NightElfFemaleNakedTorsoSkin00_00.blp. etc. If no pants, Character\NightElf\Female\NightElfFemaleNakedPelvisSkin00_00.blp. (This basically means that characters only wear underwear when they aren't wearing other clothes. Kinky.) These underwear textures also must be palettized without alpha, which presents a problem for people who modify skins. If you want to make an underwear-less skin for a character with naughty-bits, not only must you add the naughty bits to the base skin, but you must then make versions of the underwear textures that don't have underwear and that have the naughty bits.
Clothing textures are a bit more complicated. Clothing textures need to be palettized, and they can optionally (usually) have an alpha channel. These textures are drawn on top of the base skin. Clothing textures are broken into a number of different regions on character's bodies. A single piece of armor can have many different textures. For example, a long sleeve shirt would require a TorsoUpper, TorsoLower, ArmUpper, and ArmLower texture. In addition, each of these textures can have different versions for male and female players, or can be unisex.
The last paragraph was a lot of information so lets look at an example. These are the textures that make up "Padded Armor" (a cloth chestpiece) when worn on a female character:
Item\TextureComponents\TorsoUpperTexture\Cloth_B_01Brown_Chest_TU_F.blp
Item\TextureComponents\TorsoLowerTexture\Cloth_B_01Brown_Chest_TL_F.blp
Item\TextureComponents\ArmUpperTexture\Cloth_B_01Brown_Chest_AU_U.blp
There are several things to notice about these. First, each texture region has its own subdirectory. Second, this armor is short-sleeved: no ArmLower component. Third, two of these textures have male/female versions, but one is used for both sexes. You can tell by the last letter of the texture: F for "female" and U for "unisex" (and M for "male"). Important: this "sex suffix" is only a naming convention, it doesn't define what the game looks for. We players don't have any control over whether or not a given texture is male/female/both--that is defined elsewhere. (This is why clothing packs that make armor specifically for one sex often end up making that armor look terrible for the other sex.)
Part 4: BLP Files
So far we've covered how to get the files we want and how to make it so WoW loads our own versions of them. However, there are no programs which let you edit these textures directly because they are in Blizzard's proprietary BLP format. Thus, we need a converter that will convert BLP files into something common and back.
First, though, a little bit about the different BLP formats that are available to us. Basically, there are two main options: whether or not a texture is palettized, and whether or not it has alpha. BLP files can handle all 4 cases, but WoW often expects a given texture to have a particular format. For example, character skins must be palettized and have no alpha.
Back to BLP converters. There are a few BLP converters out there but I'm only going to mention the one called BLPConverter. (BLPConverter | World of Warcraft Tools | World of Warcraft @ Curse.com) Other ones exist but this one gives you the most options and feedback about what it is doing. BLPConverter only converts between BLP and PNG files, so you will need a texture editor that handles PNG. Most good ones do. If you need a good texture editor I recommend using The Gimp, as it is pretty good and totally free! (GIMP - The GNU Image Manipulation Program)
Converting files is the single thing that people get caught up on the most, so it deserves to spoken about in greater detail. Basically, the problem is that the set of capabilities of the BLP file format doesn't exactly match the capabilities of the PNG format. (Or any other, for that matter.) This means that converter programs have to do some guessing, and can never handle 100% of the possible cases. However, if you follow a simple rule you'll (probably) not have any problems at all. That rule is: never create new PNGs from scratch, but instead create copy other ones that were converted from BLPs. Lets say for example we want to make a brand new character skin that is scaly. I may not want to use the source texture at all, but if I start with the PNG created by converting the original texture I insure two things. First, the texture will be the right size. Second, the PNG will obviously be in a format that the converter knows how to use--it created it! So long as I don't change the PNG format within my graphics program I shouldn't have any trouble converting it into a BLP that the game likes.
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Note: Latest version of blpconverter (7.1) is already setup to use teh better conversion type - just drag you png (doesnt need to be index) on to the .exe file and it will generate the blp files
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Tool Links:
MyWarcraftStudio
WoW Model Viewer
BLPConverter
WinMPQ (Kodo's "myWinMPQ" version)